What are the benefits of proton beam therapy for esophageal cancer?

The treatment strategy for esophageal cancer evolves continuously, with radiotherapy having an irreplaceable position. The growing availability of proton beam therapy raises the timely question of its real benefit. The answer is substantially complicated by a number of circumstances - multiple areas of indication for use, inconsistent dosage strategies, little evidence of dose escalation benefit, and nonuniform determination of target volumes. The dosimetric advantages of proton beam therapy over conventional photon radiotherapy are clear and convincing. To date, the issue of demonstrating dosimetric advantages in the clinical practice has largely been addressed in small, retrospectively analyzed cohorts. For trimodal therapy (chemoradiotherapy + surgery), it was necessary to create special evaluation tools (TTB - total toxicity burden and POC - perioperative complications). In the setting of greatly inhomogeneous cohorts and large dose variability, it has been possible to demonstrate a reduction in toxicity with proton beam therapy compared to conventional radiotherapy. In the form of a randomized trial, the benefit of proton beam therapy has been demonstrated only once, and it was in the context of trimodal therapy. Here, the benefit also consisted in a significant reduction in toxicity. Additional randomized trials are being conducted. The issue is further complicated by expanding scanning techniques, whereas the results so far have been based on scattering techniques. The current use of proton beam therapy in esophageal cancer has so far provided evidence of lower toxicity. The evidence of other benefits of proton beam therapy is at the level of clinical research, with the basic principles of radiotherapy per se, particularly dose escalation, being at the same level of research.

Keywords: esophageal cancer, proton radiotherapy, trimodal therapy, elective nodal irradiation, dose escalation, perioperative toxicity, scattering, scanning.